Communication networks typically include devices, such as firewalls, routers, switches or gateways, which transfer or switch data, such as packets, from one or more sources to one or more destinations. A firewall or gateway device, for example, may permit, deny, encrypt, decrypt, or proxy traffic between different security domains based upon a set of rules and other criteria.
Entities, such as corporations, may use firewall/gateway devices to limit access to resources. For example, a firewall may be used to block access to certain external websites by employees. A firewall or gateway device may also be used to limit the use of a particular resource. For example, video sessions using certain video codecs (video coder-decoder protocols) may be blocked.